This application is based on and claims priority under 35 U.S.C. xc2xa7 119 with respect to Japanese Application No. 2000-022498 filed on Jan. 31, 2000, the entire content of which is incorporated herein by reference.
The present invention generally relates to internal combustion engines. More particularly, the present invention pertains to a valve timing regulation device that controls the opening and closing timing of the valve in an internal combustion engine valve system.
One example of a known valve timing regulation device is disclosed in Japanese Patent Laid-Open Publication No. Hei. 11(1999)-294121. This valve timing regulation device includes a housing member placed in a driving force transmission path which transmits a driving force from the driving shaft (i.e., crank shaft) of an internal combustion engine to a driven shaft (i.e., cam shaft) for opening and closing an exhaust valve of the internal combustion engine. The housing member is adapted to rotate together with one of the driving shaft and the driven shaft. A rotor member is assembled to a shoe portion of the housing member so as to be rotated relative thereto, and the rotor member has a vane portion which divides an advance angle fluid chamber and a retard angle fluid chamber in the housing member. The rotor member is adapted to rotate together with the other of the driving shaft and the driven shaft. A fluid pressure circuit controls the supply and drainage of an operating fluid to and from each of the advance angle fluid chamber and the retard angle fluid chamber.
This valve timing regulation device further includes a lock mechanism controlled by the fluid pressure circuit and a torsion spring. The lock mechanism prevents relative rotation between the housing member and the rotor member at the most advance angle region. The torsion spring is interposed between the housing member and the rotor member for urging the rotor member in an advancing direction relative to the housing member.
However, in this known valve timing regulation device, although the rotor member is adapted to rotate relative to the housing member for advancing the angular position of the driven shaft relative to the driving shaft, in cases where, for example, the resistance of the passage ranging from the engine driven fluid pump to the advance angle fluid chamber is very high or where the operation fluid possesses a high viscosity (e.g., the operation fluid possesses a low temperature), during a transition period at initiation of the internal combustion engine the pressure of the operating fluid supplied from the fluid pump to the advance angle fluid chamber increases to a predetermined value, it is possible that the rotor member may not correctly rotate relative to the housing member, to the most advance angle region at which the lock mechanism functions. The resulting phenomena prolongs the overlap period under which the intake and exhaust valves of the internal combustion engine open concurrently, thereby not obtaining a normal burn in the internal combustion engine upon start thereof.
Thus, a need exists for a valve timing regulation device which is not as susceptible to the foregoing disadvantages and difficulties.
According to one aspect of the invention, a valve timing regulation device includes a housing member, a rotor member, a lock mechanism and a fluid control circuit. The housing member is positioned in a driving force transmission path in which a driving force is transmitted from a driving shaft of an internal combustion engine to a driven shaft for opening and closing a valve of the internal combustion engine, with the housing member being rotatable together with one of the driving shaft and the driven shaft. The rotor member is assembled to a shoe portion of the housing member and is rotatable relative to the housing member. The rotor member has a vane portion dividing the interior of the housing member into an advance angle fluid chamber and a retard angle fluid chamber. The rotor member is rotatable together with the other of the driving shaft and the driven shaft. The lock mechanism regulates the relative rotation between the housing member and the rotor member at a region other than a most retard angle region. The fluid pressure circuit controls the supply and drainage of an operating fluid to and from each of the advance angle fluid chamber and the retard angle fluid chamber. The fluid pressure circuit includes a fluid pump driven by the internal combustion engine, a control valve which controls, by adjustment of the operating fluid supplied from the fluid pump, the supply and drainage of the operating fluid to and from each of the advance angle fluid chamber and the retard angle fluid chamber, with the control valve controlling the lock and unlock of the lock mechanism, and a check valve disposed between the control valve and the fluid pump such that the check valve is positioned close to the control valve for preventing entrance of the operating fluid into the fluid pump.
According to another aspect of the invention, a valve timing regulating device includes a housing member, a rotor member, a chamber disposed between the housing member and the rotor member, a dividing member dividing the chamber into an advance angle fluid chamber and a retard angle fluid chamber, a fluid pressure supplying device that supplies operation fluid to the advance angle fluid chamber and/or the retard angle fluid chamber respectively, a regulating member that regulates the operation fluid supplied to the advance angle fluid chamber and/or the retard angle fluid chamber, and a preventing device that prevents the operating fluid from being drained from one of the advance chamber or the retard chamber.
According to a still further aspect of the present invention, a valve timing regulation device includes a housing member, a rotor member, a lock mechanism, a fluid pump, a control valve and a check valve. The housing member is positioned in a driving force transmission path in which a driving force is transmitted from a driving shaft of an internal combustion engine to a driven shaft for opening and closing a valve of the internal combustion engine, with the housing member being rotatable together with one of the driving shaft and the driven shaft. The rotor member is positioned within the housing and is rotatable together with the other of the driving shaft and the driven shaft to rotate relative to the housing. The rotor member includes a plurality of vane portions dividing the interior of the housing member into a plurality of advance angle fluid chambers and a plurality of retard angle fluid chambers. The lock mechanism prevents relative rotation between the housing member and the rotor member. The fluid pump is driven by the internal combustion engine to pump operating fluid into the advance angle fluid chambers and the retard angle fluid chambers, and the control valve is positioned between the pump and the advance and retard angle fluid chambers to control supply and drainage of the operating fluid to and from each of the advance and retard angle fluid chambers. The check valve is disposed between the control valve and the fluid pump at a location closer to the control valve than the fluid pump to prevent entrance of the operating fluid into the fluid pump.
With the present invention, in the transition period in which the pressure of the operating fluid outputted from the fluid pump (fluid pressure supplying means) toward the advance angle fluid chamber increases to the predetermined value when the internal combustion engine is initiated or started, the torque fluctuation transmitted from the valve to the driven shaft (and the rotor member) causes repetitive relative rotations between the housing member and the rotor member. Thus, the vane (the dividing member) changes the volume of the advance and retard angle fluid chambers repetitively. The resulting repetitive pressure (negative pressure) changes in the advance and retard angle fluid chambers and the function of the check valve (the preventing means) prevents the operation fluid from being drained from the advance or retard angle fluid chamber to the fluid pump (the fluid supplying means), and establishes pumping action (sucking action) which results in repetitive suctions of the operating fluid into the advance or retard angle fluid chamber by way of the check valve (the preventing means) and the control valve (the regulating member), thereby storing the operating fluid in the advance or retard angle fluid chamber in a stepwise manner.